The present invention relates generally to supplemental restraint systems for protecting occupants of vehicles, and more particularly to a supplemental restraint system having a side airbag with a construction that improves the safety of the occupants.
Supplemental restraint systems (SRS) in vehicles are well known. A typical SRS includes one or more crash sensors and one or more airbags that are deployed when the crash sensors detect a vehicle impact event. Specifically, the crash sensors detect a vehicle impact event as defined by a series of predetermined parameters, e.g. a threshold G level. During this event, the SRS usually causes one or more of the airbags to suddenly inflate. Typically, the system holds gas within the airbag for a predetermined amount of time and then permits the gas to be forced out of the airbag. The occupant can force gas out of the inflated airbag when he is forced onto the airbag. As a result, the airbag can absorb a portion of the energy associated with the impact and decrease the risk of injury to the occupant.
Conventional side airbag construction typically includes an upper portion in open communication with a lower portion. The upper portion typically is intended to protect the occupant's shoulders while the lower portion ordinarily is utilized for protecting the occupant's ribs and remaining thorax region. This construction typically has a constant thickness from the upper portion to the lower portion. As is known, the pressure within the airbag remains relatively constant throughout the airbag. For this reason, the upper portion and the lower portion apply the same amount of pressure to the occupant's shoulders and ribs.
A drawback of existing side airbags is that its uniform thickness may not adequately protect the occupant. Specifically, during the initial stages of a side impact event, the occupant's shoulder can be pressed laterally into the side airbag so as to force gas from the upper portion of the airbag into the lower portion of the airbag. As a result, the lower portion can be momentarily inflated thicker than the upper portion and contact the occupant's ribs. It is understood that the occupant's shoulder can withstand a substantially stronger blow without injury than the ribs can. For this reason, the lower portion may inflate outward and deflect the occupant's weaker ribs toward the center of the vehicle. Such a result can produce a substantial amount of spine shear and possibly injure the occupant.
One proposed solution requires that the overall bag pressure is decreased by utilizing a lower-powered inflation device. However, the decreased airbag pressure may allow the upper portion of the airbag to become completely collapsed thereby allowing the occupant's shoulder to be contacted by door intrusion. As a result, the door intrusion can cause excessive shoulder deflection and possibly injure the occupant.
Therefore, a need exists for a side airbag having a construction that sufficiently decreases the risk of injury to the occupant.